MILESTONE STUDY is dedicated to problems connected with patients with multivessel coronary artery disease and/or with left main narrowing who present symptoms of acute ischemia. For such kind of patients according to current ACC/AHA guidelines CABG (surgical revascularization) is recommended as a treatment method. In comparison with CABG, recent studies have shown that PCI (percutaneous coronary intervention) is associated with a lower rate of periprocedural adverse events and similar long term event-free survival in patients with left main disease. Our latest non randomized registry and randomized LEMANS study, comparing LMCA (left main coronary artery) stenting with CABG confirmed above findings. LEMANS ACS (acute coronary syndrome) retrospective registry of patients with UPLMCA (unprotected LMCA) disease and non ST elevation ACS showed lower 30 day and trend toward lower one year mortality after PCI when compared with CABG. It should be stressed, that acute ischemia substantially increase the risk of CABG. In fact, there are limited data on the outcome of ULMCA stenting or CABG in patients with acute coronary syndromes (ACS).